WELL; The Fitness Oracle

By GRETCHEN REYNOLDS

Published: April 28, 2013

We know that stretching before exercise tends to be counterproductive because, in loosening muscles, it also temporarily weakens them. But whether you should stretch at other times — after exercise, for instance, or first thing in the morning or just before bed — is murkier, in part because studies of stretching have not been standardized. Some have had young, healthy volunteers stretch for 20 minutes or more; others for 5 minutes or less. Still others have used older, stiffer volunteers or people with existing injuries. Not surprisingly, the results have been inconsistent. Even within the same study, people respond quite differently to stretching, with some showing increased flexibility and others not.

Still, the consensus among scientists who study stretching is that the practice has benefits. It reduces muscle soreness due to strenuous exercise, for one thing (although, according to a 2011 review, only by about 1 point on a 100-point pain scale). Stretching also increases the range of motion in joints, and “maintenance of normal ranges of motion is an important fitness and wellness objective,” says Dr. Duane Knudson, chairman of the department of health and human performance at Texas State University in San Marcos. While some people anecdotally report that their joints feel permanently looser if they stretch, experiments generally find that joints restiffen within an hour.

It’s possible, however, that what you believe stretching does for your body may matter as much as what it actually does. In a 2010 study, volunteers were randomly instructed to stretch or not to stretch before exercise. Those who “strongly agreed” at the start of the study that stretching is advisable rarely reported sore muscles if they were assigned to stretch. But if they were told not to stretch, they were more likely than other volunteers to report that their muscles subsequently felt sore.

Unfortunately, the answer seems to be no. “To be quite frank, I cannot see any advantage or reason for a person to be using an exercise ball as an office chair,” says Dr. Jack P. Callaghan, the Canada Research Chair in Spine Biomechanics and Injury Prevention at the University of Waterloo in Ontario, Canada. Although you might expect that sitting on the ball would demand extra exertion to keep you upright and stable, when Callaghan and his colleagues had healthy, young volunteers sit alternately on a ball, an office chair or a backless stool while machines measured muscle activity in their abdomens and lower backs, they found no meaningful differences between the seating options; sitting on a ball did not provide a mini-workout for the midsection.

Ball chairs do not improve posture, either. Research by Callaghan and others have shown that people generally slump just as much on a ball as in a normal chair, and that back pain is not reduced. And in part because sitting on a ball involves more contact between the seating surface area and your backside than a chair does — you sink into the ball somewhat — many ball-sitters report increased discomfort in their bottoms.

On the bright side, one study from 2008 showed that clerical workers on balls burned marginally more calories than those on chairs — about four kilocalories per hour. But new research from Callaghan’s lab suggests that they may also be putting themselves in almost comical peril; he found that when workers sitting on balls reach sideways for something, they risk toppling over.

If you are sitting too much, a better solution is to stand up periodically throughout the day, which has been found to improve health. Prop your keyboard on a shelf or filing cabinet and type upright. Or stand when you make phone calls.

But don’t overdo the standing, Callaghan says. Many people experience back pain if they stand for two hours or more at a workstation. Aim, instead, for perhaps 15 minutes upright each hour.

For those who aren’t physiologists or exercise geeks, VO2 max is shorthand for maximal oxygen uptake, a standard measure of aerobic fitness. About half of anyone’s VO2 max is innate, genetics studies suggest; you’re born relatively more or less fit. The rest is up to you.

Until recently, most experts believed that to improve fitness, you needed to complete lengthy runs or other endurance workouts. But lately, some have begun to swear by short bursts of extremely taxing exercise, a routine known as high-intensity interval training. Whether one is more effective than the other at building endurance, however, remains in dispute. “There is not a lot of scientific literature” directly comparing the two, says Dr. Martin Gibala, chairman of the department of kinesiology at McMaster University in Hamilton, Ontario.

He does, however, vote for intervals. Data from his lab show that even a few minutes a week of high-intensity intervals can “increase VO2 max to the same extent” as many hours a week of more-moderate, prolonged endurance training. Other scientists have found that intervals can even elicit greater increases in VO2 max than longer, slower workouts, if the total energy output is the same. This means that, per minute, you get more physiological bang from intervals, an important consideration if your exercise time is limited. “Of course,” Gibala adds, “it is probably most effective” to deploy both intervals and traditional longer workouts.